Magnetic latch and lock

ABSTRACT

This latch and lock means includes a magnetized bolt and a strike in which at least a part thereof is either magnetized and of opposite polarity from the bolt or is of material magnetically attractable to the bolt. The bolt is movable in a bolt housing of magnetically attractable material. It is moved by magnetic attraction to a door locking position within the strike member when it is aligned with the same by closing of the door and is yieldingly held there by magnetic attraction. In addition pawl means is provided to positively secure the bolt against retraction by picking methods using thin instruments inserted between the edge of the door and the jamb. Extensible pull back members, normally held contracted relative to each other by spring means, will first release the pawl means and then retract the bolt in response to a key or knob actuated pull. Magnetic attraction between the bolt and bolt housing will hold the bolt retracted when the door is open.

United States Patent 11 Graham I 1 Feb. 26, 1974 1 1 MAGNETIC LATCH AND LOCK [57] ABSTRACT [76] Inventor: Percy R. Graham, 7342 24th Ave. This latch and lock means includes a magnetized bolt N.W., Seattle, Wash. 98117 and a strike in which at least a part thereof is either magnetized and of opposite polarity from the bolt or is [22] Flled' 1972 of material magnetically attractable to the bolt. The [21] App]. No.: 314,087 bolt is movable in a bolt housing of magnetically attractable material. It is moved by magnetic attraction f Apphcat'on Data to a door locking position within the strike member [63] comnuauonm'part of Sen 2961827 when it is aligned with the same by closing of the door 1972 abandoned and is yieldingly held there by magnetic attraction. In addition pawl means is provided to positively secure 52 us. 01. 292/251.5, 292/l69.14, 70/151 R the bolt against retraction by picking methods using [51] f Cl Eosc 17/56 EOSC 19/16 E05c 1/12 thin instruments inserted between the edge of the door [58] held of 292/251'5 16914 70/151 R and the jamb. Extensible pull back members, normally 1 held contracted relative to each other by spring [56] References C'ted means, will first release the pawl means and then re- UNITED STATES PATENTS tract the bolt in response to a key or knob actuated 3,516,701 6/1970 Graham 292/251.5 X pull. Magnetic attraction between the bolt and bolt 2,853,331 9/1958 Teetor 292/251.5 housing will hold the bolt retracted when'the door is 812,871 2/1906 Papen Foth.... 70 151 R x open, 3,273,925 9/1966 Graham 292/201 Primary Examiner.loseph' H. McGlynn Assistant ExaminerRichard P. Tremblay Attorney, Agent, or FirmFred C. Matheny 7 Claims, 14 Drawing Figures PAIENIEDFEBZEW 3.794.366

SHEET- 2 0F 2 Fig. 4 I

. Fig. 6

MAGNETIC LATCH AND LOCK This application is a continuation in part of my prior patent application Ser. No. 296,827, Filed Oct. 12, 1972, for a magnetic Latch and Lock now abandoned.

SUMMARY OF THE INVENTION An object of my invention is to provide a magnetic door latch or lock mechanism in which a bolt is held, by magnetic force, in a locked position within a strike member when a door by which the bolt is carried is fully closed and is held, by magnetic force in a retracted position in which it is out of sight and out of the way when the door is in any open position.

Another object is to provide a latch or lock means in which a bolt is moved into and yielding held within a strike receptacle in a locked position by magnetic force and in which said bolt is further secured in a locked position by mechanical deviced which function like pawls and render said bolt substantially proff against picking by the use of thin instruments of a type sometimes inserted in cracks between a door and a door jamb or parts-of a door jamb to push a bolt back but in which the bolt is readily retractable by key or knob operated pull back means.

i I I Another object is to provide a latch or lock in which a bolt is moved to and yieldingly held in a locked position by magnetic attraction and is also positively dogged in the locked position by pawl means and in which longitudbally extensible and contractable pull back means is connected with the bolt and carries spring pressed devices which, when a pull is exerted on the pull back means, will disengage the pawl means and in so doing will release the bolt for retraction by the pull back means.

Other objects are to provide a magnetic door latch and lock which is neat in appearance, smooth, quiet and efficient in operation, not expensive to manufacture, easy to install in doors and door jambs and one in which neither the lock or strike mechanism has any parts which protrude when the door is open and on which clothing and like articles can catch.

Other objects will be apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in longitudinal section, with parts in elevation, taken ina vertical plane and showing latch or lock and strike means embodying my invention as they may appear when installed in a door and a door jamb and in a locked position, fragments only of the door and door jamb being shown.

FIG. 2 is a longitudinal sectional view, with parts in elevation, taken substantially on line 22 of FIG. 1, and showing bolt pull back means partly retracted.

FIG. 3 is a view similar to FIG. 2 showing the bolt and bolt pull back means fully retracted.

FIG. 4 is a detached top edge view, with parts in section, showing a lock bolt and a first pull back member.

FIG. 5 is an end view of the bolt shownin FIG. 4. FIG. 6 is a side view of said bolt and first pull back member looking in the direction indicated by line 6-6 of FIG. 4.

FIG. 7 is a sectional view taken on line 77 of FIG. 6.

FIG. 8 is a detached side view of a pawl used in this lock.

FIG. 9 is an edge view of said pawl.

FIG. l0is a cross sectional view taken on line l0 10 of FIG. 2.

FIG. 11 is a cross section taken on line 11-11 of FIG. 2.

FIG. 12 is a detached view in side elevation showing a second pull back member.

FIG. 13 is a detached elevation view of a smaller spring abutment disc used in the invention.

FIG. 14 is an edge view of the disc looking in the direction indicated by line 1414 of FIG. 13.

Like reference numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 the numeral 15 indicates a fragment of a door and 16 a fragment of a door jamb. The forward edge portion of the door and the oppossed edge portion of the door jamb are each mortised and bored or recessed in the usual way to receive parts of the latch or lock and strike mechanism hereinafter described. The strike mechanism comprises a strike plate 17 having in it a bolt receiving opeining 18. A cup shaped receptacle 19 having on it outwardly extending flanges 20 is secured, as by welding or brazing, to the back fact of the strike plate 17 and forms a housing for a member 21, which may be either a magnet or a body of magnetically attracable material and is rigid with or may be a part of receptacle 19. The member 21 is shaped and dimensioned so that its face is positioned far enough back in the receptacle 19 to provide a bolt receiving opening of substantial depth. Screws 22 secure the strike plate 17 to jamb l6.

This latch and lock mechanism comprises a tubular bolt housing 23 of magnetically attractable material, open and having an external flange 24 at its outer end, shown at the leftin FIGS. 1, 2 and 3. Said housing 23 has a partly closed inner end 25 provided with a rectan-. gular opening 26. The inner end portion of bolt housing 23 is provided with external angularly extending elements 27 which are suitably shaped and positioned for engagement by conventional knob spindle housing means 28 which extends cross-wise of the door 15 and a fragment of which is shown by dash lines in FIG. 1. The flanges 24 on the outer end of the bolt housing 23 is trapped and rigidly and permanently held between two face plate members 29 and 30 which are rigidly secured together so that the bolt housing 23 and the two face plate members form a permanently assembled part of the latch and lock. At the time of installation the bolt housing 23 fits within a suitable bored hole in the edge portion of the door and the face plate formed by members 29 and 30 fits within a mortised recess in the front edge of the door and is secured to the door by screws 31.

A bolt 32 of generally cylindrical cross section but which is herein shown as having two flat opposed faces 33 is slidably disposed in the bolt housing 23. The bolt accommodation openings in face plate members 23 and 30 and in strike plate 17 are preferably similarly flattened to conform with the bolt 32. The outer end of the bolt 32 is magnetized, preferably be embedding in it a magnet 34, FIGS. 4 and 5, which is covered by a thin, permanently attached plate 35. The bolt 32 will be strongly attracted magnetically to the strike member when said bolt and the strike member are aligned and close together, as they will be when the door is fully closed and this will be true regardless of whether the part of the strike member to which the bolt is attracted is a magnet or is a body of magnetically attractable material. The bolt housing 23, being of magnetically attractable material, will cause bolt 32 to move to and remain in a retracted position when the door is open and the bolt 32 and strike part 21 are disaligned.

A first pull back member 36 of flat material is rigid with the inner end of the bolt 32 and extends rearwardly therefrom. Preferably the rear end of said first pull back member 36 has a V-shaped notch 37 in it, FIG. 4, and is also provided with oppositely projecting lugs 38. Said pull back member 36 is further provided, near the rear end of the bolt 32, with two other transversely extending lugs or brackets 40 each having in it a perforation 41 to receive a pivot member 42 on which a pawl 43 is pivotally mounted. The two brackets 40 are diametrically oppositely positioned and the two pawls 43 extend in opposite directions and each pawl has on it a tooth 43, positioned to engage with a finely toothed or roughened surface 58 in the bolt housing 23. A second pull back member 44, also of flat material, is shown detached in FIG. 12. Said member 44 has in it a longitudinal slot 45 which extends fron one end thereof throughout the major portion of its length and is correctly dimensioned to fit over and slidably mount the second pull back member 44 on the first pull back member 36. Two lugs 46 extend sidewise from the respective edges of the second pull back member 44 at the end thereof nearest to the bolt 32. Two notches 47 are provided in the respective edges of said member 44 near its opposite end. A stake 48 protrudes from the second pull back member 44 near the end thereof shown at the right in FIGS. 1, 2, 3 and 12 and serves as a stop to limit movement of said member 44 into the bolt housing 23. Pawls 43 are made of magnetically attractable material.

A larger disc 50 of flat metal, which functions as a spring abutment member, has in its central portion an opening 51, FIG. 10, shaped like a cross which fits over and slidably mounts the disc on the two pull back members 36 and 44. The side of the disc 50 remote from the bolt 32 has a narrow, marginal flange 52 which cooperates with the disc in forming a shallow cup to receive the larger end of a cone shaped compression spring 53. Two parallel arms 54 are secured to the marginal parts of the disc 50 and extend toward the bolt, 32 and lie alongside of the flat sides 33 of said bolt. The outer end of each arm 54 has on it a lug 55 which is adapted to engage with one of the pawls 43 when the arm 54 is retracted and disengage a tooth 43, of the pawl from a finely toothed or roughened surface 56 in the bolt housing 23. The pawls 43 are yieldingly held in engagement with the toothed surfaces 58 by magnetic attraction between the bolt 32 and said pawls and when said pawls are thus held in engagment with toothed surfaces 58 they dog the bolt in its outwardly projected, locked position. Obviously springs could be used to yielding hold the pawls 43 in their dogging engagement with toothed or roughened surfaces 58. The larger disc 50 serves as an abutment member for one end of spring 53, and as a carrier for arms 54 which bring about the release of pawls 43 from toothed surfaces 58 in response to key or knob actuated force exerted on second pull back member 44.

The smaller end of the conical spring 53 rests against the smaller abutment member or disc 56 which is suitably notched so it can be applied to and will fit over the two pull back members 36 and 44 and will rest against the lugs 38 on the inner end of the first pull back member 36. Also it will permit the first pull back member member 21 when it is moved close to and into alignment with said member 21 by closing the door 15 is substantially greater than any retractile force which can'be exerted on the bolt by the spring 53 and any counter magnetic force acting on said bolt.'When the door is open the bolt 32 will be held retracted by magnetic attraction between magnet 34 and bolt housing 23 and a small force exerted by spring 53. When the door 15 is moved from an open to a closed position the bolt 32 will be magnetically drawn into therecess 18 in strike plate 17 and securely held against members 21, as shown in P10. 1. In this position the spring 53 will be partly compressed and will be holding the arms 54, 55 clear of the pawls 43 and magnetic attraction between the bolt 32 and said pawls will be holding said pawls in engagement with the finely toothed surfaces 58 of housing 23. This will prevent retraction of bolt 32 by using picking devices to contact it and push it back.

However, when the parts are in the locked position just described, if a key or knob actuated pull is exerted on the second pull back member 44 said member 44 and the larger abutment disc 50 will be moved retractively, spring 53 will be further compressed and will be flattened between the two abutment discs 50 and 56 and pawls 43 will be moved to and held in a disengaged position by lugs 55 on arms 54. This brings the several parts to the intermediate position, as shown in FIG. 2. A further pull exerted on pull back member 44 will then overcome the magnetic attraction between magnet 34 and member 21 and retract the bolt 32. The conical shape of the spring 53 makes possible its use in a spaceof short length and making the pawls 43 of magnetically attractable material makes it possible to use the magnetism of the bolt 32 to hold them in dogging position.

I claim:

1. ln magnetic latch and lock means for installation in a door and door jamb, a bolt housing applicable to the door and composed at least partly of magnetically attractable material and having a bolt accommodation opening positioned substantially flush with the edge of the door; a bolt movable longitudinally in said housing and having a magnetized outer end portion movable in said bolt accommodation opening between a retracted position and an outwardly protruding position relative to the edge of the door; a strike member applicable to the door jamband magnetically attractable relative to the bolt, said strike member having a bolt receiving opening positioned to register with the bolt accommodation opening in the lock housing when the door is closed, said bolt being held retracted by magnetic attraction between the bolt and bolt housing when the member being operable in overcoming the magnetic attraction between said bolt and said bolt housing and moving said bolt into and holding it in said strike member when the door is closed and said bolt is close to and aligned with said strike member; a first pull back member secured to the inner end of said bolt; a second pull back member positioned in overlapping relation to said first pull back member and extending beyond the inner rial and being yieldingly urged into bolt dogging posi-.

tion by the magnetic attraction of said magnetized bolt and means connected with said manually operated bolt retracting devices operable in disengaging said bolt dogging means before retractile movement of the bolt occurs when a bolt retracting force is exerted on said bolt retracting devices.

2. The magnetic latch and lock means as claimed in claim 1 in which at least part of the strike member is magnetized and is of opposite polarity from the magnetized end portion of the bolt.

3. The magnetic latch and lock means as claimed in claim 1 in which at least part of the strike member is composed of material which is magnetically attractable to the magnetized end portion of the bolt.

4. A magnetic latch and lock for application to a door and door jamb comprising a bolt housing composed at least partly of magnetically attractable material applicable to the door and having in one end thereof a bolt accomodation opening substantially flish with the edge of the door; a bolt longitudinally movable in said bolt housing, said bolt having a magnetized outer end portion movable between an outwardly projecting position and. a retracted position relative to the edge of the door; a strike member applicable to the door jamb and magnetically attractable relative to the bolt, said strike member having a bolt receiving opening positioned so as to register with the bolt accommodation opening in the bolt-housing when the door is closed, said bolt being held retracted by magnetic attraction between the bolt and bolt housing when the door is open and the bolt and strike member are dis-aligned and said strike end of and movable lengthwise relative to said first pull back member; pawl means connected with said first pull back member and bolt operable in dogging said bolt in an outwardly protruding locked position; two spring abutment members connected respectively with the overlapping end portions of said two pull back members and movable with said pull back members; a compression spring on said pull back members and expansively operable between said two abutment members in yieldingly urging said two pull back members into shortened overall relation to each other; said two spring abutment members and said compression spring being operable as stop means in limiting overall elongation of said two pull back members and pawl releasing means movable retractively with said second pull back member and operable in disengaging said pawl means and freeing said bolt and first pull back member for retraction.

5. The latch and lock means as claimed in claim 4 in which one of said pull back members has a longitudinal slot in it and the other pull back member fits slidably within said slot.

6. The latch and lock as claimed in claim 4 in which the pawl releasing devices are arms carried by the spring abutment member that is connected with said second pull back member.

7. The latch and lock means as claimed in claim 4 in which the compression spring is of conical shape, whereby it is compressable into a substantially flat condition between said two spring abutment members and cooperates with said spring abutment members ,in forming stop means limiting overall elongation of said .two pull back members. 

1. In magnetic latch and lock means for installation in a door and door jamb, a bolt housing applicable to the door and composed at least partly of magnetically attractable material and having a bolt accommodation opening positioned substantially flush with the edge of the door; a bolt movable longitudinally in said housing and having a magnetized outer end portion movable in said bolt accommodation opening between a retracted position and an outwardly protruding position relative to the edge of the door; a strike member applicable to the door jamb and magnetically attractable relative to the bolt, said strike member having a bolt receiving opening positioned to register with the bolt accommodation opening in the lock housing when the door is closed, said bolt being held retracted by magnetic attraction between the bolt and bolt housing when the door is open and the bolt and strike member are dis-aligned and said strike member being operable in overcoming the magnetic attraction between said bolt and bolt housing and moving said bolt into and holding it within said strike member when said bolt is close to and aligned with said strike member; manually operable bolt retracting devices connected with said bolt; bolt dogging means connected with said bolt normally operable in holding said bolt in an outwardly projected locked position, said bolt dogging means being composed at least partly of magnetically attractable material and being yieldingly urged into bolt dogging position by the magnetic attraction of said magnetized bolt and means connected with said manually operated bolt retracting devices operable in disengaging said bolt dogging means before retractile movement of the bolt occurs when a bolt retracting force is exerted on said bolt retracting devices.
 2. The magnetic latch and lock means as claimed in claim 1 in which at least part of the strike member is magnetized and is of opposite polarity from the magnetized end portion of the bolt.
 3. The magnetic latch and lock means as claimed in claim 1 in which at least part of the strike meMber is composed of material which is magnetically attractable to the magnetized end portion of the bolt.
 4. A magnetic latch and lock for application to a door and door jamb comprising a bolt housing composed at least partly of magnetically attractable material applicable to the door and having in one end thereof a bolt accomodation opening substantially flish with the edge of the door; a bolt longitudinally movable in said bolt housing, said bolt having a magnetized outer end portion movable between an outwardly projecting position and a retracted position relative to the edge of the door; a strike member applicable to the door jamb and magnetically attractable relative to the bolt, said strike member having a bolt receiving opening positioned so as to register with the bolt accommodation opening in the bolt housing when the door is closed, said bolt being held retracted by magnetic attraction between the bolt and bolt housing when the door is open and the bolt and strike member are dis-aligned and said strike member being operable in overcoming the magnetic attraction between said bolt and said bolt housing and moving said bolt into and holding it in said strike member when the door is closed and said bolt is close to and aligned with said strike member; a first pull back member secured to the inner end of said bolt; a second pull back member positioned in overlapping relation to said first pull back member and extending beyond the inner end of and movable lengthwise relative to said first pull back member; pawl means connected with said first pull back member and bolt operable in dogging said bolt in an outwardly protruding locked position; two spring abutment members connected respectively with the overlapping end portions of said two pull back members and movable with said pull back members; a compression spring on said pull back members and expansively operable between said two abutment members in yieldingly urging said two pull back members into shortened overall relation to each other; said two spring abutment members and said compression spring being operable as stop means in limiting overall elongation of said two pull back members and pawl releasing means movable retractively with said second pull back member and operable in disengaging said pawl means and freeing said bolt and first pull back member for retraction.
 5. The latch and lock means as claimed in claim 4 in which one of said pull back members has a longitudinal slot in it and the other pull back member fits slidably within said slot.
 6. The latch and lock as claimed in claim 4 in which the pawl releasing devices are arms carried by the spring abutment member that is connected with said second pull back member.
 7. The latch and lock means as claimed in claim 4 in which the compression spring is of conical shape, whereby it is compressable into a substantially flat condition between said two spring abutment members and cooperates with said spring abutment members in forming stop means limiting overall elongation of said two pull back members. 